Your sister could be a heck of an ally if you play your cards right. Dont be the angry guy, all that does is justify W desire to leave you and sister to agree with her.
Be careful in playing the jealousy game. I hinted to my W that I was interested in another woman and thats when she started going bonkers flirting. As if she now had a free pass.
Focus on yourself, be the best man you can be, improve your physique, take care of your looks, get a new hair cut, some new clothes. Look GOOD every time you see your W. Be upbeat, happy, fun...someone anyone would want to be around.
It doesnt take a rocket scientist to figure out that you are getting over her and ready for the meat market. She will realize that, and if she likes what she sees from you, she wont want you to hit the market.
Just beware trying to make her jealous.
Me: 37 Wife: 40 Son: 7yo Son: 18 mo Bomb: 12/31/07 Status: Reconciled 1/2009 but backsliding terribly right now